Metal-forming system



Dec. 29, 1970 w, sw soN 3,550,420

METAL-FORMING SYSTEM Filed Nov. 13, 1967 2 Sheets-Sheet 1 INVENTOR. Mia/w A Imus-01v Dec. 29, 1970 W. A. SWANSON METAL-FORMING SYSTEM Filed Nov. 13, 1967 2 Sheets-Sheet 2 INVENTOR. Wl/akp A jam/: 4

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United States Patent O 3,550,420 METAL-FORMING SYSTEM Wilford A. Swanson, Sunland, Calif., assignor to Michael Scott Metal Shaping, Inc., a corporation of California Filed Nov. 13, 1967, Ser. No. 682,112 Int. Cl. B21d 11/02 U.S. Cl. 72-296 3 Claims ABSTRACT OF THE DISCLOSURE A system is disclosed for forming various metal shapes, utilizing prestressing techniques. In the illustrative example of the disclosure, a section of sheet metal is formed into a U-shaped channel, which also has-a substantial variation or deviation along the length of-the channel. The structure includes means for straining the section of sheet metal along an axis to resiliently elongate the sheet of metal. A two-dimentional mechanical forming die then traverses the length of sheet metal, generally along the path of strain, whereby to shape the metal to the desired configuration. Subsequent to the shaping operation, as disclosed, the stressing forces are relieved with the result that the sheet is formed in the desired three-dimensional shape.

BACKGROUND AND SUMMARY OF THE INVENTION Metal-working machines and techniques represent a highly-developed art capable of accommodating the use of mass-production methods for many different products. However, generally, conventional metal-working machines are massive, are extremely expensive and require tremendous operating power. For example, different types of metal-working machines of large-part capability, conventionally either incorporate apparatus for heating a workpiece or alternatively they utilize huge presses capable of exerting immense distorting forces. As a result, machines of either type require considerable energy and are very expensive to operate. Therefore, a substantial need exists for a relatively-simple, economical system for providing certain sizable metal shapes without great initial expenditures for dies, heavy equipment and so on and operable at a relatively low cost.

In utilizing conventional metal-shaping techniques, considerable difficulty may be experienced in attempting to form thin sheet metal of particular types, e.g., stainless steel. For example, in working with very thin metals, large forming dies frequently tend to create wrinkles and other defects. Therefore, a considerable need exists for a metal-shaping system capable of forming thin sheets of metal into various shapes without material defects.

In general, the present invention resides in the discovery that metal can be effectively formed by applying stress which coincide with the path of a two-dimensional forming die (e.g., extrusion type) that is moved along the metal workpiece. More specifically, the present invention involves structure for straining a section of sheet metal (as long a particular path) operative with means for progressively deforming the sheet metal, including a twodimensional die and means for moving the die through a path (not necessarily linear) to define the desired shape and which path is maintained coincident with the stressing force path straining the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing, which constitutes a part of this specification, an exemplary embodiment demonstrating various objectives and features hereof is set forth, specifically:

FIG. 1 is a perspective view of an apparatus constructed in accordance with the present invention;

Patented Dec. 29, 1970 FIG. 2 is a sectional and diagrammatic view of a portion of the structure of FIG. 1 illustrating the operation of such structure;

FIG. 3 is a front elevation view of the apparatus of FIG. 1;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 3;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 3;

FIG. 8 is a sectional view taken along line 88 of FIG. 3.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT As required, a detailed illustrative embodiment of the invention is disclosed herein. However, it is to be understood that the embodiment merely exemplifies the invention which may be embodied in many forms that are radically different from the illustrative embodiment. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims defining the scope of the invention.

Referring initially to FIG. 1, there is shown an elongate sheet metal workpiece 10 which is strained by stress forces, as it is held in a supporting structure 12. While in a strained configuration, the workpiece 10 is shaped by a two-dimensional die 14 which traverses the length of the workpiece. Thus, the structure of FIG. 1 illustrates the process hereof with respect to the formation of an elongate channel member which is offset along the length thereof, i.e., the path of the die mechanism 14 is not linear. In this regard, as Will be explained in detail below, it is important to recognize that as the die mechanism 14 does not traverse a linear path, the workpiece is formed in three dimensions.

Considering the structure of FIG. 1 in somewhat greater detail, the stressing apparatus or structure 12 includes an elongate support frame 16 supporting opposed upright end brackets 18 and 20. The bracket 18 includes a face plate 22 which is back-supported by reinforcing abutments 24, that are attached to the elongate base beams 26.

The head-end face plate 22 contains a central aperture or bore which receives a force column or shaft 28 for driving a head structure 30 which carries a clamp 32. The head structure 30 also includes readwardly-extending, horizontal guide posts 34 which are matingly received through corner-disposed bores in the face plate 22.

At the opposite end (tail end) of the supporting structure 12, the bracket 20 provides a vertical face plate 36 supported by corner abutments 38. The face plate 36, in turn, supports a perpendicularly mounted beam 40, which, in turn, supports a clamp 4-2 and a pair of cable spools 44 connected to be rotated by a motor 46. The motor 46 acts through the spools 44 and parallel horizontal cables 48 to traverse the forming mechanism 14 along the workpiece 10. In this regard, the motor 46 may comprise a unit of relatively low horsepower incorporating a speed-reducing gear chain and a relatively low overload circuit breaker.

The movement of the shaping mechanism 14 along the workpiece 10 is facilitated by a supporting carriage 50. Specifically, the carriage 50 (shown at the head end) includes a platform 52 supporting an upright yoke 54 and a male two-dimensional forming die 56. The yoke 54 threadably receives a screw 58 that is topped by a handle 60, and which screw supports a female two-dimensional 3 forming. die .62 for matingly engaging the workpiece over the die 56.

The platform 52 of the carriage 50 (bearing the die structure) is supported on vertical rollers 64 and outboard horizontal rollers 66, both of which engage rails 68 defining a track along the length of the structure 12. The rails 68 are supportably affixed into the face plates 22 and 36 and additionally are supported by vertical posts 70 (of varying height) mounted under the rails along the length of the track and extending to the horizontal base beams 26.

Recapitulating, it may now be seen that the structure as shown in FIG. 1 functions to hold the workpiece 10 in a strained state, while mating dies 56 and 62 are traversed along the length of the workpiece 10. Of course, a wide variety of different structures may be provided to accomplish these operations. However, the exemplary forming machine set forth herein has been found to function effectively and may be constructed at a relatively low cost. In this regard, the structure may be made of steel, and may incorporate a hydraulic jack 72 with a manual actuator 74 to withdraw the load shaft 28 and apply the stressing force to the workpiece 10. A hydraulic input line 76 is indicated for supplying hydraulic fluid from a reservoir to the jack 72. Somewhat in this regard, it is to be noted that the stress to the workpiece 10 is applied centrally thereof, coinciding substantially to the central section which will undergo the greater distortion during the forming operation.

Just as the machine hereof may be provided in a wide variety of different forms, it may be adapted to shape workpieces into a wide variety of different forms. As indicated above, the embodiment disclosed herein functions to develop an elongate channel member which is nonlinear along its length. Specifically, the workpiece 10 may comprise thin stainless steel and may be formed as the leading edge of an airfoil.

Pursuing the exemplary structure of FIG. 1 to accomplish the exemplary workpiece 10, a complete understanding of the system may now best be perfected by considering the sequence of a cycle of operation. The initial operation involves loading the workpiece 10 into the structure as shown in FIG. 1. In this regard, the handle 60 is turned to raise the female die 64 .(as shown) so that the workpiece 10 may be passed between the dies 56 and 62, i.e., through the yoke 54. The ends of the workpiece 10 next are engaged by the clamps 32 and 42 at the head end and tail-end respectively of the machine. Specifically, the tail-end (right, as shown) of the workpiece 10 is fitted into the jaws 78 of the clamp 42 and the handle 80 of the clamp is turned so that the jaws 78 firmly grasp the workpiece 10. At the opposite end (head) the workpiece 10 is set in the clamp 32 so that the jaws 84 lockingly engage the workpiece while the load shaft 28 is inward.

Next, the hydraulic jack 72 is manually driven, through the actuator 74, to withdraw the load shaft 28, moving the head structure 30 to a position as indicated in phantom in FIG. 2. As a result, the workpiece 10 is strained along a path extending between the clamps 32 and 42, which strain path is distorted to a nonlinear form during the actual shaping of the workpiece 10.

The degree to which the workpiece 10 is strained varies widely depending upon the material in the workpiece and the nature of the shaping operation. However, in general it has been found desirable to strain the workpiece substantially to the threshold of its elastic limit.

The next step in the process involves the initial deformation of the workpiece 10 between the dies 56 and 62 (FIG. 4). This deformation is accomplished by carefully turning the handle 60 to drive the screw 58 downward so that it carries the die 62 into mating engagement with the die 56, with the workpiece 10 therebetween. In this regard, it is to be noted that the dies 62 and 56 are completely closed. on the workpiece 10 (FIG.

5). However, both the leading edges 86 and the trailing edges 88 of the mating die surfaces are somewhat relieved to afford a tapered guiding structure into the closed, twodimensional die passage 90.

With the dies 56 and 62 closed on the workpiece 10 (FIG. 4) the system next is actuated to form the entire length of the workpiece 10. Specifically, the motor 46 (shown in phantom, FIG. 3) is energized, causing the spools 44 to take up or draw in the cables 48, thereby pulling the carriage along the rails 68. As a result, the workpiece 10 is scanned along its length, one section at a time, traversing it through the mated dies 56 and 62. Thus, the desired shape is accomplished.

It is to be noted, that the rails 68 are offset from the horizontal and therefore extend in two dimensions. Of course, one of those dimensions is parallel to the two-dimensional passage 90 (FIG. 3) of the forming die; while the other dimension is perpendicular thereto (up and.

down). The result of the two dimensional aspect of the rails 68 is the fact that the structure hereof (although using a two dimensional forming die) may readily form workpieces in three dimensions. Specifically, the workpiece 10 is not only deformed to provide a U-channel but furthermore is also formed to include a very shallow U-shape along its length.

Considering the formative operation in greater detail, as the carriage 50 traverses the rails 68 (FIG. 3), an initial workpiece section 10a is first completely formed, as indicated in FIG. 8. The following workpiece section 10b, which lies immediately before the die forming passage 90, is slightly tapered as indicated in FIG. 7, as it is guiding into the dies. Well ahead of the dies, the workpiece section is substantially unaffected as shown in FIG. 6.

Asthe carriage 50 traverses the full length of the workpiece 10, the workpiece is formed to the desired configuration. As the carriage 50 encounters the rise and drop in the rails 68, such a rise and drop are incorporated in the shape of the workpiece 10, as indicated above. However, it is important to recognize that the path of strain through the workpiece 10 is essentially coincident with the instantaneous forming position of the dies 56 and 62.

On traversing the workpiece 10 (completing the forming operation), the drive motor 46 (FIG. 3) may be cut off automatically by any of a variety of switching structures or simply by allowing the carriage 50 to reach the end of the rails 68 at which the motor 46 becomes overloaded and automatically cuts off.

At the conclusion of the forming operation the hydraulic jack 72 is relieved, thereby allowing the head 30 to be moved inwardly by the'elastic force of the workpiece 10. Thereafter, the workpiece 10 is removed simply by releasing the clamps 32 and 42 and the mating dies 56 and 62.

Subsequently, the workpiece 10 may be trimmed at its sides and ends, to formulate the desired member. How ever, obviously, such finish process steps will depend entirely upon the specific nature of the workpiece 10 and its contemplated application.

From a consideration of the above, it may be seen that the structure hereof may be employed, utilizing the process hereof to accomplish three-dimensional metal shapes with relatively inexpensive tooling and equipment. Furthermore, considerable experience and experimentation with the subject hereof has indicated that workpieces may be formed to exceedingly high standards. In this regard, the system hereof is capable of completing high-tolerance jobs both with regard to specified shapes and with regard to defects.

Of course, as indicated above, the system hereof may be readily adapted to provide a wide variety of different shapes and may be incorporated in a wide variety of different machines; therefore, the system as disclosed herein is to be deemed merely an exemplary embodiment and the scope hereof shall not be restricted accordingly butrather shall be interpreted in accordance with the claims set forth below:

What is claimed is:

1. A process of forming a substantially uniform thickness, elongated sheet of nonductile metal, as stainless steel, comprising the steps of:

straining said elongated sheet of metal along the length thereof, to the threshold of its elastic limit thereof to thereby resiliently elongate said sheet of metal; matingly engaging a two dimensional forming die to said sheet of metal to deform a portion of said sheet transversely to the length thereof and thereby shape a section of said sheet;

traveling said two dimensional forming dies along the length of said sheet of metal to transversely deform said sheet along its length; and

relieving said sheet of metal from strain.

2. A process according to claim 1, further including the step of directing said forming die to travel along a nonlinear path whereby to distort said sheet of metal along the length thereof.

3. A metal-forming apparatus for distortedly shaping a section of uniform thickness sheet metal having nonductile characteristics, as stainless steel, to form a predetermined form, comprising:

stress means for straining said section of sheet metal along a path lying substantially along the length thereof to the threshold of the elastic limit;

distortion die means for engaging said sheet metal to distort a segment thereof, transversely to the length of said sheet, which distortion die extends to shape said sheet along two dimensions that are transverse to said path of strain; and

means for moving said distortion die means in relation to said section of sheet metal along a nonlinear path whereby to progressively distort said section of sheet metal transversely and along the length thereof to provide a predetermined form.

References Cited UNITED STATES PATENTS 2,872,964 2/1959 Hollis 72297 2,986,194 5/1961 De Marco 72297 3,257,832 6/1966 Harvey 72297 CHARLES W. LANHAM, Primary Examiner M. J. KEENAN, Assistant Examiner US. Cl. X.R. 

